As a hot-spot research subject in today's communication standardization field, NGN adopts IP packet technology as the carrier network technology and combines fixed communication technology and mobile communication technology. NGN can provide more abundant multimedia services, such as emerging services with real-time requirement (e.g. IP TV, video conferencing, multimedia remote teaching and video-on-demand), these services require the communication network to provide highly efficient end-to-end Quality of Service (QoS) support, and meanwhile the customer has increasingly higher requirements on network service quality. Therefore, how to provide end-to-end QoS support may be one of the core issues of NGN.
The International Telecommunication Union-Telecommunications Standardization Sector (ITU-T), as the telecommunications unit of the International Telecommunication Union (ITU), has developed a standard regarding resource and admission control. The latest draft of Resource and Admission Control Functions (RACF) issued by ITU-T provides a RACF-specific functional framework as shown in FIG. 1, which is a functional architecture diagram of RACF in pertinent prior art. The RACF comprises two parts, which are, respectively, a Policy Decision Functional Entity (PD-FE) and a Transport Resource Control Functional Entity (TRC-FE). The TRC-FE interacts with the transport function via Rc interface and interacts with the Transport Resource Enforcement Functional Entity (TRE-FE) via Rn interface. Moreover, the PD-FE interacts with the TRC-FE via Rt interface, interacts with the Customer Premises Network (CPN) via Rh interface, interacts with the Service layer's Service Control Functions (SCF) via Rs interface, and interacts with the Network Attachment Control Functions (NACF) via Ru interface. The PD-FE interacts with other Next Generation Networks via Ri interface.
In addition, the PD-FE is dependent of neither the transmission technology nor the SCF. The PD-FE makes the final decision for resource and admission control on the basis of network policy rules, service information provided by the SCF, transport layer subscription information provided by the NACF, and the result of resource availability decision provided by the TRC-FE.
The TRC-FE is independent of services, but is dependent on the transmission technology. The TRC-FE is responsible for collecting and maintaining the transmission network information and resource status information. After receiving a resource request from the PD-FE, the TRC-FE enforces resource-based admission and control on the basis of QoS, priority requirement, resource availability information and transmission-related policy rules.
The transport layer comprises a Policy Enforcement Functional Entity (PE-FE) and a Transport Resource Enforcement Functional Entity (TRE-FE). The PE-FE is a packet-to-packet gateway, which may be located between a Customer Premises Network (CPN) and an access network, between an access network and a core network, or between networks of different operators, and is the key node which supports dynamic QoS control, port address translation control and Network Address Translator (NAT) crossing. The TRE-FE enforces the transport resource policy rules sent down by the TRC-FE. The scope, function and the Rn interface of the TRE-FE, which need further research, are not the research object of R2 stage.
FIG. 2 shows a resource request process in the pull mode in prior art. As shown in FIG. 2, the resource request process comprises the following steps:
Step S202, A transport layer signaling from the Customer Premises Equipment (CPE) triggers the PE-FE to generate a resource decision request so as to reserve required QoS resources for the specified flow.
Step S204, After receiving a QoS request from the CPE, the PE-FE sends the PD-FE a resource decision request message via the Rw interface to request the PD-FE to make an admission control decision. The resource decision request message comprises flow description and QoS parameter information.
Step S206, If the SCF has provided QoS pre-authorization to the related flow, the PD-FE, after receiving the resource decision request message from the PE-FE, interacts with the SCF so as to obtain the service information of related flow. Step S206 is optional.
Step S208, The PD-FE checks the flow description, the requested QoS resource and the service information to see if they are consistent with the network policy rules in the PD-FE and with the transport layer subscription information in the NACF.
Step S210, Under the condition that the check in Step S208 has passed, the PD-FE determines the access network and the core network required by media flow and interacts with the TRC-FE to check the availability of resources.
Step S212, After Step S208 and Step S210, the PD-FE makes a final admission decision.
Step S214, The PD-FE sends a resource decision response message to the PE-FE, and the message contains the final decision rules. Then, the PE-FE performs policy installation and replies to the CPE through the transport layer signaling.
It has been seen from the above mentioned process that in existing Rw interface protocol, the CCR command can be used for the PE-FE to send a resource decision request message to the PD-FE in the pull mode (i.e. Step S204). However, the CCR command provides no clear definition about how to include the flow description and QoS parameter information, and, in the pull mode, in addition to the flow description and QoS parameter information, it is also required to include other information such as flow status, user name, IP address, logical access ID, and physical access ID, etc. Unfortunately, these are not yet defined in the existing Rw interface protocol.
In pertinent prior art, although the resource request process in the pull mode is given, the QoS request information from the transport layer has not been accurately represented. Therefore, it is still problematic in actually implementing the above mentioned process.